Isopropyl iodide → 8-Oxo-2,2-dimethyl-7alpha-isopropyl-3-oxa-1-azabicyclo[4.2.0]octane

Participants

Reaction Conditions

Reaction Steps

THF, 20 ml is placed under N2, treated with 1.54 ml diisopropylamine and cooled to -78° C. A solution of n-butyl lithium 1.97 M in hexane 5.6 ml is added dropwise over 5 min. The reaction mixture is stirred at -78° C. for 10 min. and then treated with 8-oxo-2,2-dimethyl-3-oxa-1-azabicyclo[4.2.0]octane 1.55 g in 15 ml THF added dropwise over 5 min. After another 10 min. hexamethylphosphoramide 1.97 ml is added. The mixture is stirred another 10 min., then treated with 2 ml of isopropyl iodide. The reaction mixture is stirred at -78° C. for 15 min. and allowed to warm to 25° C. and stirred for 15 min. The reaction mixture is diluted with EtOAc, washed once with pH 7 phosphate buffer then dried and evaporated. The residue is chromatographed on silica gel using 25% EtOAc/C6H6 as eluant to give 8-oxo-2,2-dimethyl-7α-isopropyl-3-oxa-1-azabicyclo[4.2.0]-octane. μ i.r.: 5.7 (β-lactam). n.m.r. δ: 0.96d, 1.06d ##STR15## 1.4S, 1.76S (gem dimethyl);

Provenance & Evidence